Compounds of the formula ##STR2## are disclosed by a number of references. Thus, Cannon et al. (J. Med. Chem. 19, 987 (1976)) describe i.a. compounds wherein R.sup.I is CH.sub.3 and Y.sup.I and Y.sup.II are both H, Y.sup.I is 7--OH (or 7--OCH.sub.3) and Y.sup.II is H, or Y.sup.I is 8--OH (or 8--OCH.sub.3) and Y.sup.II is H, or Y.sup.I is 7--OH (or 7--OCH.sub.3) and Y.sup.II is 8--OH (or 8--OCH.sub.3). Further, compounds wherein R.sup.I is H, C.sub.2 H.sub.5, n--C.sub.3 H.sub.7 or benzyl and Y.sup.I is 7--OH (or 7--OCH.sub.3) and Y.sup.II is 8--OH (or 8--OCH.sub.3), respectively, have been described by Cannon et al. (J. Med. Chem. 22, 341 (1979)). Said compounds are indicated to have central dopaminergic properties although the monohydroxy compounds are reported to be only weakly active and the non-hydroxy compound to be inactive.
Cannon et al. (J. Med. Chem. 23, 1 (1980)) also describe compounds wherein Y.sup.I is 8--OH (or 8--OCH.sub.3), Y.sup.II is 9--OH (or 9--OCH.sub.3) and R.sup.I is H, CH.sub.3, C.sub.2 H.sub.5 or n--C.sub.3 H.sub.7. Said compounds are claimed to be inactive in the central nervous system but to be potent dopamine agonists in the periphery.
Wikstrom et al. (J. Med. Chem., 1982, 25, 925-931) describe compounds under the above formula wherein Y.sup.II is H, Y.sup.I is 7--OH, 8--OH, 9--OH and 10--OH and R.sup.I is n--Pr and n--Bu having dopaminergic properties. However, these compounds stimulate both presynaptic and postsynaptic dopamine receptors. The hydroxy compounds mentioned were prepared by demethylating the corresponding methoxy compounds. In the preparation of those methoxy compounds, intermediates are employed wherein Y.sup.II is H, Y.sup.I is CH.sub.3 O and R.sup.I is H.
DE Offenlegungsschrift No. 20 44 172 describes compounds under the formula ##STR3## wherein R.sup.I and R.sup.II represent H or alkyl, X.sup.I represents H.sub.2 or O and Y.sup.I represents H, alkoxy or hydroxy. Said compounds are claimed to have analgesic activity.